This invention relates to heat exchangers, and in particular, to plate and fin type heat exchangers such as the type used with internal combustion engines for cooling engine coolant.
In the past, engine coolant heat exchangers, such as radiators, have been made by providing a plurality of parallel, spaced-apart flat tubes with cooling fins located therebetween to form a core. Opposed ends of the tubes pass through openings formed in manifolds or headers located on each side of the core at the respective ends of the tubes. A difficulty with this type of construction is that the tube to header joints are difficult to fabricate and prone to leakage.
A method of overcoming these difficulties is shown in U.S. Pat. No. 3,265,126 issued to D. M. Donaldson. In this patent, headers are provided with a continuous longitudinal opening, and the tubes are formed with specially shaped ends to fit into this continuous opening, thus simplifying the assembly and reducing the leakage problem. A difficulty with the Donaldson structure, however, is that the shape of the various components is quite complex resulting in high tooling costs.
The present invention is a heat exchanger of universal application where relatively simple and inexpensive tooling is required to make heat exchangers of different types and even with differing sizes and configurations.
According to one aspect of the invention, there is provided a heat exchanger comprising a plurality of stacked plate pairs formed of mating plates having central planar portions and raised peripheral edge portions. The edge portions are joined together in mating plates to define a flow channel between the plates. The plates have offset end flanges, the respective flanges at each end of each plate pair diverging. The flanges have lateral edge portions extending from root areas located at the joined peripheral edge portions. The end flanges also have transverse distal edge portions joined together in back-to-back stacked plate pairs to space the plate pairs apart and form transverse flow passages between the plate pairs. Opposed U-shaped channels enclose the respective end flanges of the plate pairs. The channels have rear walls spaced from the plate end flanges and side walls joined to the flange lateral edge portions covering the root areas. The U-shaped channels have open ends. End plates close the U-shaped channel open ends to form manifolds. Also, the manifolds define inlet and outlet openings therein for the flow of fluid through the plate pairs.
According to another aspect of the invention, there is provided a method of making a heat exchanger comprising the steps of providing an elongate strip of plate material having a planar central portion and raised peripheral edge portions. The plate material is cut into predetermined lengths. The plate lengths are formed with offset end flanges extending in a direction away from the peripheral edge portions. The plate lengths are arranged into plate pairs with the offset end flanges diverging and the plate peripheral edge portions in contact. The plate pairs are stacked so that the end flanges engage to space the plate pairs apart. U-shaped channels are provided to enclose the plate offset end flanges, the channels having open ends. The channel open ends are closed to form manifolds, and inlet and outlet openings are formed in the manifolds. The plates and manifolds are joined together to form a sealed heat exchanger.